1. Field of the Invention
The present invention relates to a method of stimulation for generating a given tactile effect on the finger of a user which is acting on a key of a static keyboard, for example for re-creating a feeling of force and rupture similar to that provided by conventional push-buttons (particularly of the deformable capsule type).
It also relates to a device specially designed for implementing this method.
2. Description of the Prior Art
Generally, a static keyboard usually comprises a rigid surface possibly mounted on a force measuring system and covered with a so-called "tactile" surface for making and localizing the selections. This keyboard may further comprise a grid for guiding the bearing pressure and defining the zones forming the keys, this grid being added to the tactile surface or forming an integral part thereof.
It is clear that, because it is static, this keyboard does not make it possible to generate on the finger of the operator which is acting on a key a physiological stimulus for example for acknowledging, validating or even indicating that the desired function has been carried out or is being carried out.
This is why means have been associated with the keyboard for causing a shock or transmitting vibrations at a suitable chosen point of the keyboard which are perceptible by a finger acting on a key.
Now, it proves that this solution has a number of drawbacks:
The amplitude of the vibrations or shocks exerted on the keyboard must be relatively low (and so practically imperceptible) so as not to disturb the operation of the keyboard and, in particular, the tactile surface. PA0 For this reason, these vibrations are difficult to detect by a user wearing gloves. PA0 When the keyboard is mounted on a structure subjected to vibrations, it becomes difficult to distinguish the vibrations triggered off by actuation of a key from the vibrations transmitted by the structure. PA0 This solution which is not entirely satisfactory from the ergonomic point of view does not make it possible to re-create sensations similar to that of conventional push-buttons with which users are familiar. PA0 a static type keyboard comprising a plurality of keys, PA0 a mobile assembly including all or part of the keyboard, PA0 detection means for detecting at least one of the components of the stresses undergone by the keyboard following the action of an operator on the key of the keyboard, PA0 an actuator adapted for generating a pre-determined movement of the mobile assembly, and PA0 an electronic circuit for controlling the actuator as a function of the signal delivered by the detector and/or the state of the switching device associated with the key of the keyboard which has been actuated.
It has also been proposed, particularly in the Review "IBM Technical Disclosure" (Bulletin, vol 20, no. Jul. 2, 1977 New York US, pages 708-709) a method for generating a given effect on the finger of a user which is acting on a key (5) of a static keyboard, this method consisting in making at least a part (1) of the keyboard mobile on which the finger of the user bears at least partially when it actuates a key, and in causing a movement of the keyboard during such actuation. In this case, the movement is triggered by the contact caused by the actuated key.
Considering the mobility of the keyboard under the effect of actuation, this solution has in particular the drawback of requiring relatively sensitive keys which, when they are actuated, must cause switching before the assisted movement of the mobile part of the keyboard occurs, the system not having to take into account possible switching during the outgoing and return travel of the mobile part of the keyboard.
For this reason, this solution remains subject to undesirable switching, possibly due to vibrations.